1. Field of the Invention
Various therapeutic and diagnostic medical procedures involve accessing a vein or artery through a percutaneous tissue track. Femoral arteries are commonly accessed during various procedures, such as angiograms, angioplasties, catheterization and peripheral artery angioplasty. Accessing the blood vessel typically includes insertion of a relatively large diameter introducer sheath along the percutaneous tissue track and into an access opening in the blood vessel. Medical instruments, including guidewires and various catheters, are then introduced into the patient""s vascular system through the introducer sheath.
At the conclusion of the medical procedure, the introducer sheath is removed leaving a relatively large access opening in the vessel wall which must be closed to stop bleeding. This has been traditionally accomplished through the use of digital pressure at the puncture site. This, however, requires that direct pressure be applied for an extended period of time, such as 45 minutes to an hour, to effectively stop bleeding from the access opening. Mechanical substitutes for finger pressure have been used, but can be uncomfortable for the patient. Using digital pressure to stop bleeding is not only expensive from the standpoint of the time of the trained medical person applying the pressure, it is also quite physically difficult to maintain a constant pressure at the puncture site for such an extended period. In addition, applying direct pressure to the puncture site causes the vessel being accessed to be blocked which can create its own problems, such as ischemia.
An early alternative to direct pressure to stop bleeding from an access opening in a blood vessel was the use of biodegradable collagen plugs. These plugs are either applied directly on top of the puncture site in the vessel wall, or are secured to the wall with a suture and polymer anchor. In the latter device, the polymer anchor is placed within the artery, against the inner wall of the artery. While such devices worked, the plug and/or anchors could cause complications.
In lieu of applying direct pressure to the puncture site, tissue glues and hemostatic materials have been used to halt blood flow from the blood vessel access opening. These materials are typically positioned along the percutaneous tissue track using a balloon catheter, the balloon being situated at the distal end of the catheter within the blood vessel. When the balloon is inflated, it effectively seals the opening in the blood vessel to permit the hemostatic material to be properly positioned at the access opening in the blood vessel without being introduced into the vessel. After a period of time, the balloon is deflated and the balloon catheter is withdrawn from the blood vessel and tissue track. These devices require a very small balloon and can be expensive.
For these reasons, it would be desirable to provide improved systems and methods for sealing vascular penetrations, such as vascular penetrations in the femoral artery, after performing various intravascular procedures such as angiography, angioplasty, stent placement, aneurysm treatment, and the like. It would be particularly beneficial to provide methods and systems which could reliably seal such vascular penetration sites using materials which would be substantially or completely resorbed over time, thus reducing the risk of complications associated with implantation of materials at the penetration site. It would still further be desirable to provide methods and systems which promote natural healing of the vascular penetration site and associated tissue tract through the activation and stimulation of the clotting cascade at the region of vascular penetration. At least several of these objectives will be met by the inventions described hereinafter.
2. Description of the Background Art
Methods and systems for delivering hemostatic agents to blood vessel penetrations are described in U.S. Pat. Nos. 6,193,670; 6,045,570; 5,855,559; and 5,728,132. A device employing an articulated foot for suturing vascular penetrations is described in U.S. Pat. Nos. 5,752,979; 5,653,730; 5,626,601; 5,591,205; 5,486,195; 5,419,765; 5,413,571; 5,383,896; 5,370,660; 5,330,446; 5,221,259; 4,744,364; and European Patent 493 810B1.
The present invention provides systems and methods for delivering a flowable hemostatic gel to an outside (anterior) side of a vascular penetration. The vascular penetration is typically positioned at the distal or remote end of a tissue tract which has been formed to provide access to the underlying blood vessel, typically a femoral or other artery which has been accessed in order to perform an intravascular procedure, such as angiography, angioplasty, stent placement, aneurysmal repair, neurological interventions, intravascular cardiac bypass, or other cardiac and peripheral vascular procedures which are known in the art or may be devised in the future. In general, both the systems and the methods rely on the positioning of a barrier on an inside (posterior) side of the blood vessel penetration in order to provide a temporary seal of the penetration. After the barrier is in place, the flowable hemostatic gel will be delivered over the barrier to a region directly over the anterior side of the vascular penetration. The barrier will be able to contain the flowable hemostatic gel, substantially inhibiting or preventing any leakage, migration, or intrusion of the gel into the underlying blood vessel lumen. The barrier, however, will also permit the passage of a controlled amount of blood from the blood vessel back into the tissue tract where it can combine with the hemostatic gel to promote coagulation of the gel and healing of the vascular penetration and tissue tract. After the hemostatic gel has been delivered and xe2x80x9cset,xe2x80x9d typically taking from one to several minutes, the barrier will be removed, leaving the gel in place to continue coagulation and healing of the penetration. In particular, after the relative short setting period, the gel will be sufficiently solidified to inhibit or prevent back bleeding into the tissue tract, thus reducing or eliminating the need to apply pressure to the penetration.
Suitable hemostatic gels will comprise a biologically compatible matrix, typically a cross-linked protein, such as gelatin, collagen, albumin, or the like, which is hydrated or hydratable to form the structural component of the gel over the vascular penetration as described above. The hemostatic gel will typically also include an active component, usually a protein involved in the clotting cascade, most usually being thrombin, to promote clotting of the gel when exposed to blood. A particularly suitable flowable gel is described in U.S. Pat. Nos. 6,063,061 and 6,066,325, assigned to the Assignee of the present application, the full disclosures of which are incorporated herein by reference. Suitable materials as described in these patents are commercially available under the trade name FloSeal(trademark) from Fusion Medical Technologies, Inc., the Assignee of the present Application. Other suitable plug-forming materials include glues or sealants comprising naturally occurring coagulation proteins, such as fibrinogen and/or thrombin, or commercially available synthetic solvents, such as those available under the tradenames Coseal(trademark) and Focalseal(trademark).
The vascular penetrations to be sealed may be formed by any conventional access technique, such as the Seldinger technique where the tissue tract and vascular penetration are first formed using a needle and subsequently dilated using a suitable dilation cannula. The tissue tracts will thus pass through a layer of muscle tissue overlying the target blood vessel. In the case of the femoral artery, access will usually be gained through the patient""s groin where the length of the tissue tract is typically from 5 to 20 cm, depending on the size of the patient and angle at which the artery is approached. Penetration through the blood vessel will have an outside, i.e. a side adjacent to the distal or remote end of the tissue tract, and an inside, i.e. a side which is within the blood vessel. As described above, the flowable hemostatic gel of the present invention will be delivered to a region which generally overlies the outside of the blood vessel penetration.
In order to deliver the flowable hemostatic gel to the outside side of the vascular penetration without significant passage of the gel into the blood vessel lumen, a barrier is placed across the side of the penetration located on the inside of the blood vessel. The barrier may be any structure which will inhibit or prevent the flow, migration, or intrusion of the gel into the blood vessel lumen. The structure of the barrier must be suitable for delivery through the tissue tract and subsequent deployment across the vascular penetration. The first type of barrier may comprise a flexible element, such as a semipermeable membrane, mesh, mallecott structure, or the like. Such structures will be porous or foramenous with pore or aperture sizes selected to permit blood flow out of the blood vessel while inhibiting the passage of the gel into the blood vessel. Alternatively, the barriers can be solid and/or rigid non-porous structures having one or several discrete passages therethrough which are sized to permit blood flow while inhibiting the passage of the flowable gel into the blood vessel. In an exemplary embodiment, the barrier is a solid articulated foot (as described in detail below) having a single circular aperture with a diameter of about 0.1 mm.
In a first specific aspect, the present invention provides a system for delivering the flowable gel comprising an elongate barrier carrier in a delivery tube. The elongate barrier carrier is positionable through the tissue tract and includes the deployable barrier attached at or near its distal end. The barrier may be any of the barriers described above. The delivery tube is positionable in the tissue tract simultaneously with the elongate barrier carrier and includes a passage for delivery of the hemostatic gel to the outside of the vascular penetration. The passage is typically an elongate lumen within the delivery tube, and the delivery tube can be configured to lie in parallel with the elongate barrier carrier, coaxially over the elongate barrier carrier, or preferably coaxially within the central lumen of the elongate barrier carrier.
The barrier carrier will typically include a mechanism for deploying the barrier, i.e. expanding, extending, or positioning the carrier across the inside of the vascular penetration. Particular examples of the barrier and deployment mechanism comprise generally tubular mesh which can be axially contracted to cause radial expansion, as generally shown in FIGS. 1-4, 6, and 11-12 hereinafter. Alternatively, the barrier can be mallecott-type structure as shown in FIGS. 13A, 13B, 14 and 14B. In a presently preferred embodiments, the barrier is generally a solid foot which is pivotally attached to a shaft to permit deployment within the blood vessel, as illustrated in FIGS. 17-20 and 22-28 hereinafter.
In the second aspect of the system of the present invention, the delivery tube may include a blood reservoir which collects blood with a distal end of the delivery tube as positioned in the lumen of the blood vessel. The presence of blood in the reservoir will be visually discernable so that entry of the distal end of the delivery tube into the blood vessel can be confirmed. Usually, the reservoir will include a resiliently expandable structure which permits filling of the reservoir at arterial blood pressures which will empty the reservoir at pressures below arterial blood pressure. The presence of such a structure provides certain advantages. The first advantage is that, while the distal end of the delivery tube lies within the blood vessel, the amount of blood in the reservoir will vary as a result of the natural pulsation of arterial pressure, e.g. between 30 mm Hg to about 120 mm Hg. Accidental or intentional removal of the distal of the delivery tube from the blood vessel lumen will cause such pulsation""s to cease and eventually permit the resilient structure to return the blood to the tissue tract at the point where the distal end of the delivery tube is positioned. The latter return of blood can be advantageous when combined with delivery of the hemostatic agent, where the blood can provide an initial bolus of blood to initiate clotting with the hemostatic gel.
In a still further aspect of the present invention, methods for delivering the hemostatic gel to the outside of the vascular penetration comprise positioning the barrier on the inside of the vascular penetration and delivering the flowable hemostatic gel to the anterior side of the penetration. The barrier may be any of the barriers described above which inhibit passage of the hemostatic gel into the blood vessel lumen but permit the flow of blood back into the tissue tract to promote clotting in the presence the hemostatic gel. The methods may further comprise collecting blood through the tissue tract prior to delivering the flowable hemostatic gel and thereafter combining the collected blood with the hemostatic gel to promote clotting. Such methods may be performed using the apparatus having the blood collection reservoirs described above. The positioning step may comprise positioning a semipermeable membrane or other porous or foramenous structure as described above, or may comprise positioning a solid barrier having at least one passage therethrough, also as described above. The flowable gel will typically comprise at least one member of the clotting cascade, typically thrombin. Gels will usually comprise a collagen or gelatin gel matrix, as described above.